Kinetic properties of ion carriers and channels

TLDR: A unified description of ion carriers, channels, and pumps seems possible based on the concept of channels with multiple conformational states based on recent work on the dynamics of proteins.

Abstract: A unified description of ion carriers, channels, and pumps seems possible based on the concept of channels with multiple conformational states. The notion of a channel with variable energy profile is suggested by recent work on the dynamics of proteins. With the exception of mobile, translatory carriers of the valinomycin type which represent a separate class of ion translocators, most transport systems in biological membranes seem to be built-in proteins. Transmembrane proteins may differ in their mode of operation by the extent to which conformational changes are involved in the translocation of the permeant. While carriers and channels in the usual sense are limiting cases of a multistate channel, many real transport systems probably function by an intermediate mechanism.